The child is hospitalized and recovering, but was infectious while traveling back to Honolulu and during visits to healthcare providers.

Health officials say measles is a highly contagious disease. It is spread by direct contact with mucus from the nose and throat of an infected person and through the air by respiratory droplets.

Persons most at risk for catching measles are those who are not vaccinated. Possible complications of measles are pneumonia, inflammation of the brain (encephalitis), ear infections, diarrhea, and death. The risk of complications from measles is highest in children who are less than a year old, pregnant women, and persons who have an impaired or weakened immune system.

"We are very concerned about the potential for additional cases of measles," said Dr. Sarah Y. Park, state epidemiologist. "This disease is so contagious that it will infect 90 percent of the contacts who are not immune. We urge people who suspect they have measles, that is, fever and widespread rash, to call their doctor right away and isolate themselves from others to help contain the spread of illness."

The symptoms of measles generally begin about 14 days (range 7 to 21 days) after a person is infected and may include the following:

Hillary Clinton's office said "nothing nefarious was at play" when the former secretary of state used her personal email address, rather than one provided by the State Department, during her four years as America's top diplomat.